The Atherosclerosis Risk in Communities (ARIC) Study was initiated in 1985 with two components: community-based surveillance and a prospective cohort study. The community surveillance aimed to monitor trends in hospitalized myocardial infarction (MI), fatal coronary heart disease (CHD) in four U.S. communities: Forsyth County, NC; Jackson, MS; suburbs of Minneapolis, MN; and Washington County, MD. Surveillance for hospitalized heart failure (HF) events was added in 2005. The communities were selected to provide data across four (4) geographic locations with a range of mortality rates, in urban, suburban, and rural settings. The cohort study aimed to investigate the risk factors for and natural history of atherosclerosis and development of clinical atherosclerosis in middle-aged white or African American adults from the same communities. The study recruited in 15,792 white or African American participants initially aged 45-64 years and selected participants received triennial clinical exams over the first ten years of the study (1987-1989, 1990-1992, 1993-1995, and 1996-1998), with a fifth clinical exam in 2011-2013, providing a rich set of data on physical, behavioral, genetic, and psychosocial factors. Since 1988, the cohort has been contacted annually and in 2011 semiannual follow-up was initiated. Findings have been presented in over 1,400 publications as of 2014. Participants were examined for evidence of subclinical atherosclerosis using B-mode ultrasound in carotid and popliteal arteries, ankle-brachial index measurement, and retinal photography and, in subsets, abdominal aortic CT, and hemostatic factors; established and putative laboratory risk markers; socioeconomic, psychological, behavioral, and environmental characteristics; and genetic factors. Examinations included a variety of components, with a grant-funded detailed cognitive function testing component added in the most recent exam during 2011-2013. Blood samples have been assayed for putative biochemical risk factors and stored for case-control studies. DNA has been extracted and lymphocytes cryopreserved (for possible immortalization) for study of candidate genes, genome-wide scanning, expression, and other ?omics investigations. Participation of the surviving cohort was 91, 82, 74, and 65% at each of the respective follow-up examinations. Since baseline, cohort members have also been contacted every 12 months to obtain information on vital status, current residence, major illness or injury, and hospitalizations occurring between contacts to identify clinical Cardiovascular Disease (CVD) events. Cohort contact was 84% at the last completed follow-up ending on December 31, 2013.